Emergency bulk liquid cargo spill prevention system

Abstract

Large bulk liquid cargo tankers are a common sight on the world's oceans and waterways. Petroleum needs worldwide have risen sharply and in order to fulfill those needs cheaply and efficiently, shipbuilders have increased the size of tankers carrying the crude oil to the point where the modern supertanker is capable of carrying millions of barrels of oil in a single trip. Such efficiency has not come without a price in that a single tank rupture can be an ecological and financial disaster. In order to minimize and even the eliminate such a disastrous event, an apparatus has been designed to be deployed inside a bulk liquid cargo tank. Should a tank be ruptured, a large expandable bladder pre-positioned within the tank would expand as oil from within the tank would pe pumped into its internal volume. The expandable bladder serves a dual purpose to act as a seal against the portion of the tank that has been ruptured eliminating the flow of oil out of the tank and seawater into the tank. The present invention is such an expandable recovery bladder with a novel bladder arrangement and a novel fiber optic sensing and control system.

Description

The present invention was first described in Disclosure Document No. 453899 filed on Mar. 29, 1999. There are no previously filed, nor currently any co-pending applications, anywhere in the world.1. Field of the InventionThe present invention relates generally to pollution prevention and, more particularly, to a bulk liquid cargo spill prevention system of the expandable bladder bladder type for a bulk liquid cargo tanker.2. Description of the Related ArtIn the related art, methods and systems for preventing or controlling the spillage of bulk liquid cargoes such as oil into the sea are well known. In fact, there are many tanker ships whereby the loss of liquid bulk cargoes, usually petroleum products, is attempted to be minimized in case of cargo tank rupture through the ship's design. The most recent and well know is the addition of a second hull to a tanker vessel whereby the outer hull protects the inner hull / cargo tank from rupture. There are also tankers designed with the carg...

AI Technical Summary

Benefits of technology

It is a feature of the present invention to provide a novel control means whereby a ruptured tank is detected automatically and said emergency expandable bladder is deployed It is another feature of the present invention to provide a novel configuration of the emergency expandable bladder whereby said bladder is fixedly connected to an interior sidewall of a liquid cargo tank and deployed slidably suspended from an overhead track.

Yet still another feature of the present invention is a system for providing and supplying an inert gas such as nitrogen to the segregated ballast tanks to reduce the oxygen content in said tank to below explosive levels.

Briefly described according to the preferred embodiment of the present invention, an emergency expandable bladder is provided comprised of a collapsible, accordion-like bladder made from a sturdy, impermeable material manufactured to conform to the individual contour of the interior of a liquid cargo tank. The bladder is attached to the interior side of the inboard sidewall of the liquid cargo tank and expands in an outboard direction as liquid from within the ruptured tank is pumped from the tank into the bladder. To ensure successful expansion of the bladder, the bladder is slidably suspended overhead from a plurality of tracks traversing the top of the tank. Suspending the bladder in this manner also ensures that the bladder can be retracted and returned to the same configuration once the tank rupture is repaired. The liquid cargo tank consists of four sidewalls, one of which is usually the ship's outer hull, a top wall, a bottom wall which is usually the ship's bottom hull, and an oil deck used to define the tank into an upper volume and a lower volume. Said expandable bladder is designed only to encapsulate said upper volume. A plurality of elongated holes in said oil deck allows free communication of liquid cargo from said upper volume to said lower volume.

Problems solved by technology

Each of these methods and designs has its limitations.

The double hull tanker significantly increases ship construction costs and seriously affects the ship's stability.

Other ship designs employing gravity means or pumps to move liquid bulk cargo to an empty ballast tank generally do so at the expense of decreasing ship stability.

However, the '353 reference indicates that this system is not fixedly connected to the interior of a cargo tank but is to be dropped through a hatch in the top of the tank when needed.

Images